Behavior of the supermolecular structure of oriented amorphous-crystalline polymers under cyclic loading

Equipment has been developed for investigating small-angle X-ray diffraction in various phases of the loading period in cyclically extended polymers. The behavior of the large-period structure of oriented polycaprolactam (kapron) films in cyclic extension has been studied. The results are compared with the data on the behavior of the same structure in static tests.Mekhanika Polimerov, Vol. 4, No. 2, pp. 195–199, 1968     

Temperature dependence of the thermophysical properties of a Teflon — Bronze antifriction material

The effect of temperature and the concentration of the dispersed metallic filler on the thermophysical properties of a Teflon-based composition have been experimentally investigated. The results of the measurements of the thermophysical characteristics of the filled and unfilled Teflon are evaluated with allowance for the thermal conductivity of the components, their physicochemical interaction, and the change in the structure of the heterogeneous systems investigated.Deceased.A. M. Gor'kii Kiev State Pedagogical Institute; Institute of Colloidal Chemistry and the Chemistry of Water, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 6, pp. 1053–1056, November–December, 1971.     

Structural stresses in composites reinforced with a system of anisotropic fibers

The effect of the anisotropy of the mechanical and thermophysical characteristics of the reinforcement on the temperature stresses in unidirectional composites has been investigated. The stresses near fibers forming a regular structure in the transverse plane are estimated as a function of the thermoelastic properties of the components and the structure parameters.Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 4, pp. 728–731, July–August, 1974.     

Fatigue properties of kapron (nylon-6) and kaprolon

It is shown that kaprolon has high fatigue strength as compared with kapron (nylon-6) and other thermoplastics. This is attributable both to its high static fatigue strength and to its high fatigue coefficient. For both kapron and kaprolon a sharp increase in hysteretic heat production is observed after critical self-heating at 15° C; in this case the endurance of both materials is low.Mekhanika Polimerov, Vol. 1, No. 2, pp. 118–122, 1965     

Effect of orientation and molecular weight on the modulus of elasticity of polymer materials

The modulus of elasticity of a perfectly crystalline polymer is calculated as a function of the orientation of the crystallites. The calculations are based on the mechanics of a micro-inhomogeneous continuum. The dependence of the modulus of elasticity on crystallite orientation and molecular weight is calculated with reference to the example of crystalline kapron.Moscow-Lenin Pedagogical Institute. Problem Laboratory of Polymer Physics. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1002–1007, November–December, 1968.     

Study of the deformation properties of certain elastic reinforced plastics films

The author describes the results of an experimental study of the stress-strain relationship in elastic plastics films reinforced with kapron (nylon 6) mesh and tested in uniaxial and biaxial tension.Mekhanika Polimerov, Vol. 2, No. 1, pp. 43–51, 1966     

Progressive necking and orientation effects in the deformation of kapron

The stretching of kapron has been investigated by x-ray structural analysis using an estimate of the degree of orientation based on development of the Debye ring. It is established that with the progressive development of a first, second and third neck there is a decrease in the width of the texture maxima (increase in the degree of preferred orientation). The width of the texture maxima varies with the relative reduction of the cross section approximately in accordance with a linear law.Mekhanika Polimerov, Vol. 1, No. 4, pp. 7–11, 1965     

Dynamic properties of some polymer materials in loading and unloading

A series of quasi-static tests have been carried out on kapron fiber, vinyl plastic, and fluoroplastic specimens with small cross sections. Stress-strain diagrams have been obtained at strain rates from 1 · 10^–3 to 1 · 10² sec^–1. In the experiments the strain rate changed sign, which corresponded to loading and unloading. In each regime the strain rate remained constant. The experimental data are analyzed using the model of a standard linear viscoelastic solid.Mekhanika Polimerov, Vol. 3, No. 1, pp. 118–122, 1967     

The relationship between stress and deformation of polymers in the linear stress state

The relation between stress, strain and strain rate is proposed as a means of describing the deformation properties of polymers. The equation describes the stress-strain curve, aftereffect, and stress relaxation in polymers. The theoretical conclusions are in good agreement with the results of creep tests on kapron (nylon-6).Mekhanika Polimerov, Vol. 1, No. 5, pp. 25–29, 1965     

On the difference in the moduli of elasticity of polyamides subjected to different kinds of deformation

Experiments to determine the moduli of elasticity of polyamides (kapron) in tension and compression are described. A substantial difference in these characteristics was detected. The modulus of elasticity in tension is 0.75–0.80 of the value of the modulus in compresion. This difference is explained by the textural characteristics of the polyamides. The use of values of the modulus of elasticity obtained by testing specimens in tension to determine the stiffness of parts working in compression give overestimated strain values.Mekhanika Polimerov, Vol. 1, No. 4, pp. 47–51, 1965     

Temperature dependence of the mechanical properties of oriented kapron fibers crosslinked with formaldehyde

Comparative regions of effective performance of oriented kapron fibers crosslinked with various amounts of formaldehyde are obtained on the basis of tensile test data in a broad temperature interval. As the degree of crosslinking increases, the region of softening of the crosslinked fibers is displaced in the direction of higher temperatures.Mekhanika Polimerov, Vol. 4, No. 2, pp. 304–308, 1968     

Investigation of the thermophysical properties of polypropylene

The temperature and pressure dependence of the thermophysical properties of isotactic polypropylene has been investigated. The experimental results are presented and discussed.Mekhanika Polimerov, Vol. 2, No. 5, pp. 793–797, 1966     

The scale effect and the statistical theory of strength of polymer coatings

As a result of normal tensile tests on coatings based on ED-6 epoxy resin and kapron applied to a metal surface it has been established that the fracture is brittle in character and accompanied by a scale effect and a regular distribution of the strength values for specimens of the same type. It is shown that the data obtained are all in good agreement with the statistical theory of strength.State All-Union Scientific-Research Technological Institute for the Repair and Maintenance of Tractors and Agricultural Machinery, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 839–843, September–October, 1968.     

Effect of fillers and solvents on the properties of polystyrene coatings

The mechanism of coating formation from solutions of atactic polystyrene in xylene and carbon tetrachloride has been investigated. It has been established that, as the filler content increases, in coatings formed from polystyrene solutions containing an evaporating solvent the growth of the internal stresses and the thermophysical characteristics is characterized by similarity of slope, as distinct from the case of coatings obtained from systems containing a polymerizing solvent. It is shown that the nature of the solvent has an important effect on the character of the interaction at the polymer—filler interface and on the structure and properties of the coatings.Kucherenko Central Scientific-Research Institute of Structural Design. Institute of Physical Chemistry, AS USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1127–1129, November–December, 1968.     

Effect of quartz sand filler on the mechanical and thermophysical properties of alkyd and epoxy coatings

The effect of a filler on the mechanical and thermophysical properties of polymer coatings has been investigated. It is shown that quartz sand particles are centers of structure formation in alkyd and epoxy coatings. It has been found that a denser, oriented, and stressed polymer structure, much exceeding the size of the individual macromolecules, is formed around the filler particles. The size of the spheres around the filler particles depends on the nature of the film-former, on the filler surface, and on the filler content. It is postulated that secondary supermolecular structures, and not individual polymer macromolecules, are adsorbed on the surface of the filler particles.Mekhanika Polimerov, Vol. 3, No. 3, pp. 507–510, 1967     

Effect of loading history on the free vibrations of an elastic-hereditary oscillator

The effect of the dynamic loading history on the free vibrations of an elastic-hereditary oscillator is examined. The response of the material is described by an integral relation of the heriditary type with an exponential-fractional relaxation kernel. An integrooperator representation of the starting equation makes it possible to obtain a closed solution to the problem of free vibrations of an elastic-heriditary oscillator for certain specific loading histories. The results are illustrated with reference to polyamide (kapron).Mekhanika Polimerov, Vol. 4, No. 2, pp. 222–226, 1968     

Thermal conductivity of reinforced media

On the basis of a model of an inhomogeneous body a solution is obtained for the problem of the temperature field and thermal conductivities of reinforced media, whose structure is formed by a doubly periodic system of n hollow cylinders of arbitrary diameter with the space between filled by a homogeneous medium. The thermophysical characteristics of the components are assumed given.Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 749–751, July–August, 1968.     

Effect of hydrostatic pressure on the density of various plastics

It is shown that application of hydrostatic pressure causes an increase in the density of ebonite but practically no change in the density of polyethylene, kapron (nylon-6), PVC, plexiglas, and FKP-1. Uniaxial compression of some materials first increases their mean density, then, at fairly high strain, causes the density to decrease. For the majority of the materials examined, the rate of this reduction in density decreases in the simultaneous presence of hydrostatic pressure.Mekhanika Polimerov, Vol. 2, No. 3, pp. 355–358, 1966     

Effect of the properties of the components and the geometric characteristics of the structure on the thermal-conductivity coefficients of glass-reinforced plastics

A method is proposed for estimating the thermal-conductivity coefficients of orthotropic composite glass-reinforced plastics with a structure composed of continually repeating units, in which the contours of the reinforcing elements can be described by a sinusoidal law. The arguments in the formulas are the relative content and thermophysical characteristics of the components and the parameters of the microstructure of the materials considered.Mekhanika Polimerov, Vol. 4, No. 1, pp. 18–23, 1968     

Procedure for measuring the thermophysical properties of polymers at high hydrostatic pressures

A procedure is suggested for determining the thermophysical properties of solids under hydrostatic pressure conditions by the instantaneous cylindrical heat source method without allowance for heat exchange at the sample-liquid boundary. A calculation performed showed that the temperature field of a cylinder of finite radius is identical to the temperature field of an infinite body up to Fo=0.05–0.07 with an accuracy far better than 0.5%. It is shown that the sample dimensions can be small thereupon at measurement times sufficient for performing the measurements on a standard apparatus of the order of 40–70 sec.Moscow Chemical Engineering Institute. Translated from Mekhanika Polimerov, Vol. 9, No. 3, pp. 568–570, May–June, 1973.